\begin{table} %t5
\caption{\label{tab5}Cluster structural parameters for NGC~6218.}
%\begin{center}
{
\begin{tabular}{lccc}
\hline\hline
Parameter & Fitted & Literature & Ref.\\ & value & value & \\
\hline
Core radius $r_{\rm c}$   & $0\farcm6$  & $0\farcm7$   & $a$\\
Tidal radius $r_{\rm t}$  & $17\farcm6$    & $20\farcm4$ & $a$\\
Half-mass radius $r_{\rm h}$ & $3\farcm0$ & $2\farcm2$& $a$\\
Central vel. disp. $\sigma_{\rm v}$ & 4.5 km~s$^{-1}$ & 4.0 km~s$^{-1}$
& $b$\\
\hline
\end{tabular}}
\parbox{7.5cm}{
$a$: Harris (1996).\\
$b$: Pryor \& Meylan (\cite{Pryor1993}).}
%\end{center}
\end{table}